Radroach

Out of the many varieties of enemies found in the Capital Wasteland, the Radroach is the one you're going to encounter first, when busting your way out of Vault 101. And you won't just encounter one or two -- you'll encounter many of them. Hopefully, you'll instantly learn the most important lesson about fighting Radroaches from the get-go. That lesson being that these foes are so weak that wasting ammunition on them is never a good idea. Instead, when you encounter them, bust out a melee weapon such as a Baseball Bat and do them in that way. You'll need that ammunition later for enemies more deserving of it.